Device and process for lighting a fluorescent discharge lamp

Abstract

There is disclosed a device and process for starting up a fluorescent discharge lamp in which a high-frequency pulse is generated having narrow voltage peaks above the voltage required to start electric discharge and broad valleys, applied to the elements of the lamp to effect start up of fluorescence and, after start-up, the voltage automatically goes back to maintenance voltage having broad peaks at the maintenance voltage and relatively narrow valleys. The automatic cutback is effected by the load introduced by the electric discharge and the feedback from the emitter of the transistor used to generate the pulse. A capacitor is serially-connected in the lamp circuit to inhibit the flow of DC current therein.

I claim: 
     
       1. A device for lighting a fluorescent discharge lamp which lamp requires a relatively high exciting voltage to initiate fluorescence and a relatively low maintenance voltage to maintain fluorescence, which device comprises: a generating means comprising a resonating circuit including a transistor for generating a high-frequency initializing pulse having relativley sharp peaks which reach a voltage above the exciting voltage when current through the transistor decays;   circuitry for applying said initializing pulse to the terminals of said fluorescent discharge lamp; and   a voltage-reducing means for reducing the voltage of the peaks of said initializing pulse to a maintenance pulse at said maintenance voltage once the lamp has been lit;   said resonating circuit comprising transformer means including a resonating coil as the sole primary winding thereon having a capacitor connected in parallel therewith, the collector of said transistor being connected to one end of said resonating coil and the base thereof being connected to the other end of said resonating coil, and with a resistance connected in series between said base and said coil;   said generating means and said voltage-reducing means comprising a feedback-signaling coil mounted on said transformer means as the sole secondary winding thereon and magnetically coupled with said resonating coil and connected with the emitter of said transistor through anti-feedback means and to the base of said transistor through serially connected capacitors;   said circuitry for applying said initializing pulse and said maintenance voltage to said flourescent discharge lamp comprising solely two terminals, said terminals being adapted to be connected to the lamp terminals one at each end of said lamp, one of the terminals of said circuitry being connected to one end of said resonating coil and having a capacitor connected in series therebetween to prevent flow of direct current into said lamp, and the other terminal of said circuitry being connected to the other end of said resonating coil;   said device being activated by a power source having one output terminal connected to one end of said resonating coil and the other output terminal connected between said serially connected capacitors, and through a serially connected resistor to one end of said feedback signalling coil.   
     
     
       2. A device of claim 1 in which the initializing pulse comprises a waveform having relatively narrow sharp peaks of high amplitude alternating with relatively broad valleys of low amplitude. 
     
     
       3. A device of claim 1 in which the maintenance pulse comprises a waveform having relatively broad peaks of high amplitude alternating with relatively narrow valleys of low amplitude. 
     
     
       4. A device of claim 2 in which the maintenance pulse comprises a waveform having relatively broad peaks of high amplitude alternating with relatively narrow valleys of low amplitude. 
     
     
       5. A device of claim 2 in which the initializing pulse has a waveform substantially as shown in FIG. 2(A). 
     
     
       6. A device of claim 3 in which the maintenance pulse has a waveform substantially as shown in FIGS. 2(B) and 2(C). 
     
     
       7. A device of claim 6 in which the maintenance pulse has a waveform substantially as shown in FIGS. 2(B) and 2(C). 
     
     
       8. A process for lighting a fluorescent discharge lamp which lamp requires a relatively high exciting voltage to initiate fluorescence and a relatively low maintainance voltage to maintain fluorescence, which process comprises: generating by means comprising a resonating circuit including a transistor a high-frequency initializing pulse having relatively sharp peaks which reach a voltage above the exciting voltage when current through the transistor decays;   applying said initiallizing pulse to the terminals of said fluorescent discharge lamp; and   reducing the voltage of the peaks of said initializing pulse to a maintenance pulse at said maintenance voltage once the lamp has been lit;   said resonating circuit comprising transformer means including a resonating coil as the sole primary winding thereon having a capacitor connected in parallel therewith, the collector of said transistor being connected to one end of said resonating coil, and the base thereof being connected to the other end of said resonating coil, and with resistance connected in series between said base and said coil;   the voltage generation and the voltage reduction being effected by a feedback-signaling coil mounted on said transformer means as the sole secondary winding thereon and magnetically coupled with said resonating coil and coupled with the emitter of said transistor through anti-feedback means and connected to the base of said transistor through serially connected capacitors;   said circuitry for applying said initiallizing pulse and said maintenance voltage to said fluorescent discharge lamp comprising solely two terminals, said terminals being adapted to be connected to the lamp terminals one at each end of said lamp, one of the terminals of said circuitry being connected to one end of said resonating coil and having a capacitor connected in series therebetween to prevent flow of direct current into said lamp, and the other terminal of said circuitry being connected to the other end of said resonating coil;   said device being activated and maintained by a power source having one output terminal connected to one end of said resonating coil and the other output terminal connected between said serially connected capacitors, and through a serially connected resistor to one end of said feedback-signalling coil.   
     
     
       9. A process of claim 8 in which the initializing pulse comprises a waveform having relatively narrow sharp peaks of high amplitude alternating with relatively broad valleys of low amplitude. 
     
     
       10. A process of claim 8 in which the maintenance pulse comprises a waveform having relatively broad peaks of high amplitude alternating with relatively narrow valleys of low amplitude. 
     
     
       11. A process of claim 9 in which the maintenance pulse comprises a waveform having relatively broad peaks of high amplitude alternating with relatively narrow valleys of low amplitude. 
     
     
       12. A process of claim 9 in which the initializing pulse has a waveform substantially as shown in FIG. 2(A). 
     
     
       13. A process of claim 10 in which the maintenance pulse has a waveform substantially as shown in FIGS. 2(B) and 2(C). 
     
     
       14. A process of claim 12 in which the maintenance pulse has a waveform substantially as shown in FIGS. 2(B) and 2(C). 
     
     
       15. A device of claim 4 in which the voltage-reducing means also causes a change in the frequency of the pulses such that the time intervals T of the waveform of the maintenance pulse are longer than those of the initializing pulse. 
     
     
       16. A device of claim 3 in which said broad peaks are approximately twice as wide as said narrow valleys. 
     
     
       17. A device of claim 4 in which said broad peaks are approximately twice as wide as said narrow valleys. 
     
     
       18. A process of claim 9 in which said broad valleys having substantially flat bottoms and substantially zero amplitudes and said narrow sharp peaks extend sharply upward from adjacent the front edges of said flat bottoms to the initializing voltage.